The present invention relates to a power steering lock apparatus for locking a steering wheel of a vehicle or the like.
Conventionally, for the purpose of preventing theft of a vehicle, there has been provided a steering lock apparatus for locking a steering wheel of the vehicle or the like. The steering lock apparatus is structured such that an engagement concave portion is provided in an outer periphery of a steering shaft rotating in accordance with a steering operation, and a lock bolt which is movable forward and backward moves forward so as to engage with the engagement concave portion if a driver carries out a stop operation of an engine of the vehicle by a key or the like, whereby the rotation of the steering shaft is restricted and the steering wheel is locked. On the other hand, if the driver carries out a start operation of the engine by the key, the lock bolt moves backward from the engagement concave portion, and the engagement is released, whereby the rotation restriction of the steering shaft is released, and the steering wheel is unlocked.
Further, in recent years, there has been in widespread use a keyless entry system enabling opening and closing a door and starting the engine without using a structural mechanical key. Further, in this keyless entry system, if an operation of an operating unit in place of a cylinder lock to which the mechanical key is inserted is detected in a certified state of a normal electronic key, the engine is started and stopped, and simultaneously, the steering wheel is locked and unlocked by the steering lock apparatus.
One of the problems which should be avoided even in a malfunction in the power steering lock apparatus applied to the keyless entry system is the engine coming to a drive state in spite of the fact that the lock bolt is set to the lock position. This prevents an accident from being caused by driving the vehicle in spite of the fact that the steering operation can not be carried out.
Accordingly, in the conventional power steering lock apparatus, in order to absolutely ensure the fact that the lock bolt does not exist at the lock position, a microcomputer is mounted on the power steering lock apparatus. Further, the structure is made such as to further monitor the microcomputer monitoring the lock state of the lock bolt by the other microcomputer.
For example, the structure is made such that two microcomputers are mounted on the power steering lock apparatus, the microcomputers mutually monitor the lock state of the lock bolt, and an assured position information of the lock bolt is transmitted to a host microcomputer mounted on the vehicle.
Alternatively, the structure is made such as to mount one microcomputer (a slave microcomputer) on the power steering lock apparatus and connect the host microcomputer mounted on the vehicle to the power steering lock apparatus, thereby directly monitoring the position of the lock bolt by both the slave microcomputer and the host microcomputer. In Japanese Unexamined Patent Publication No. 2001-001865, a supply voltage to a circuit device (a slave control part) of the lock apparatus is turned on and off by means of a switch element of a central control unit (a host control part), and a state of the lock apparatus is monitored by a sensor provided in the lock apparatus in a state that the supply voltage of the lock apparatus is turned off.
However, in the former power steering lock apparatus, since it is necessary to mount two microcomputers, there is a problem that cost is increased. Further, in the latter power steering lock apparatus, it is necessary to wire a communication wire for connecting the host microcomputer and the slave microcomputer, and a communication wire by which the host microcomputer is directly connected to a detection switch for detecting the position of the lock bolt. This causes problems that a wiring number of the communication wires is increased, an assembling workability to the vehicle is deteriorated, and the cost is increased.